19 A number of them who had been practicing sorcery brought their incantation books and burned them at a public bonfire. The value of the books was several million dollars. 20 So the message about the Lord spread widely and had a powerful effect.
The clear act of faith is what prompted such a powerful spread of the Gospel of God.
The fact that the act involved the sacrifice of such a large fortune fueled the effect of the news of Jesus.
Some would have certainly argued that the more powerful use of the books would have been to sell them and use the millions of moolah to send missionaries abroad.
But it's not money per se that funds successful missions, it is a Message accompanied by faithful men and women forfeiting their earthly fortunes and throwing their entire lot in with Jesus that often provokes the most powerful response.